This invention generally relates to an ion-implantation method, and more particularly to an ion-implantation method for forming a shallow junction, which is used in the manufacture of electronic devices.
In semiconductor processing techniques, the ion implantation is a relatively significant technique. The ion implantation can alter the electrical properties of electronic devices so as to meet the performance requirements of the electronic devices.
Currently, ion implanters mainly include three types, namely, high-energy, middle-energy, and low-energy ion implanters. The high-energy ion implanter can provide energy of about several MeV (Mega-electron-Volt); the middle-energy ion implanter can provide energy of about 10 to 200 KeV (Kilo-electron-Volt); and the low-energy ion implanter can provide energy of about 1 KeV to several hundred eV, which can be found in U.S. Pat. No. 6,441,382 (referring to column 1, lines 35-50) and U.S. Pat. No. 6,452,196 (referring to column 1, lines 55-63). Since these ion implanters provide different implantation energy ranges, they have different designs in energy supply systems and thus form substantially different types of ion implanters.
The low-energy ion implanter has emerged as the preferred implanter for forming a shallow junction on integrated circuits, e.g., on the source/drain of transistors so as to reduce the leakage problem caused by the shrinkage of device size. Since a middle-energy ion implanter cannot be reconstructed as a low-energy ion implanter, generally manufacturers must purchase a new low-energy ion implanter. However, the low-energy ion implanter is very expensive. Therefore, under the condition that the manufacturer cannot purchase a new one, utilizing the high-energy or middle-energy ion implanter to achieve the object of forming a shallow junction has become a serious problem in ion-implantation processes.